Transcript Science_Short - LIGO

Science Opportunities for
Australia
Advanced
LIGO
Barry Barish
Director, LIGO
LIGO-G030506-00-M
Canberra, Australia
16-Sept-03
1
Astrophysical Sources
signatures

Compact binary inspiral: “chirps”
» NS-NS waveforms are well described
» BH-BH need better waveforms
» search technique: matched templates

Supernovae / GRBs:
“bursts”
» burst signals in coincidence with signals in
electromagnetic radiation
» prompt alarm (~ one hour) with neutrino
detectors

Pulsars in our galaxy:
“periodic”
» search for observed neutron stars
(frequency, doppler shift)
» all sky search (computing challenge)
» r-modes

Cosmological Signal “stochastic background”
2
Early Universe: “correlated noise”
‘Murmurs’ from the Big Bang
Cosmic
Microwave
background
WMAP 2003
3
International Network on Earth
simultaneously detect signal
LIGO
GEO
decompose
detection
locatethe
the
confidence
polarization
sources
of
gravitational waves
Virgo
TAMA
AIGO
4
Detecting a passing wave ….
Free masses
5
Detecting a passing wave ….
Interferometer
6
Interferometer Concept
 Arms in LIGO are 4km
 Laser used to
measure relative  Measure difference in
lengths of two
length to one part in
orthogonal arms
1021 or 10-18 meters
…causing the
interference
pattern to change
at the photodiode
As a wave
Suspended
passes, the
Masses
arm
lengths
change in
different
ways….
7
How Small is 10-18 Meter?
One meter ~ 40 inches
 10,000
100
Human hair ~ 100 microns
Wavelength of light ~ 1 micron
 10,000
Atomic diameter 10-10 m
 100,000
Nuclear diameter 10-15 m
 1,000
LIGO sensitivity 10-18 m
8
International Network
LIGO
Hanford
Observatory
MIT
Caltech
Livingston
Observatory
9
LIGO Livingston Observatory
10
LIGO Hanford Observatory
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LIGO Optics
fused silica
 Surface uniformity < 1 nm
rms
 Scatter < 50 ppm
 Absorption < 2 ppm
 ROC matched < 3%
 Internal mode Q’s > 2 x 106
Caltech data
CSIRO data
12
What Limits LIGO Sensitivity?

Seismic noise limits low
frequencies

Thermal Noise limits
middle frequencies

Quantum nature of light
(Shot Noise) limits high
frequencies

Technical issues alignment, electronics,
acoustics, etc limit us
before we reach these
design goals
13
Advanced LIGO
improved subsystems
Multiple Suspensions
Active Seismic
Sapphire Optics
Higher Power Laser
14
Advanced LIGO
2007 +
Enhanced Systems
• laser
• suspension
• seismic isolation
• test mass
Rate
Improvement
~ 104
+
narrow band
optical configuration
15
Advanced LIGO
Cubic Law for “Window” on the Universe
Improve amplitude
sensitivity by a
factor of 10x…
…number of
sources goes up
1000x!
Virgo cluster
Initial
LIGO
Advanced
LIGO
16
Gravitational Waves
A New Window on the Universe
Advanced LIGO
will provide a new
way to view the
dynamics of the
Universe
17